During surgery a patient's temperature is normally monitored as by a rectal probe or a probe inserted into an ear cavity, the probe often being in the form of a thermistor wired to appropriate temperature indicating and/or recording equipment. The anesthetist, having primary concern with monitoring and maintaining vital functions of the patient during surgery, is of course concerned with any changes in the patient's temperature. While rectal and ear temperature sensors normally function properly during an operation, they may become unseated and fail to correctly sense the patient's temperature, and when this occurs the sensor must be reseated by a nurse or other attendant as the anesthetist is otherwise occupied with administering the anesthetic and oxygen. Additionally, rectal and ear probes may cause discomfort to the patient and irritation which may continue to cause discomfort after the patient has come out of the anesthetic, resulting in increased trauma. Finally, rectal, ear, and other types of temperature sensors add to the amount of equipment needed during surgery, and tend to further complicate the procedures.
By combining a temperature sensor with a typical endotracheal tube more reliable monitoring of the patient's temperature may be obtained during surgery, in part because the person immediately concerned with monitoring the patient's vital signs, the anesthetist, has the temperature sensor under his immediate control and is constantly at hand to make necessary adjustments in the equipment during the surgery. Fewer pieces of equipment are necessary when the temperature sensor is combined with the endotracheal tube than when a rectal or ear sensor must be provided in addition to the endotracheal tube, and since fewer portions of the patient's body are affected by use of the combined temperature sensor and endotracheal tube unit than with the other types of sensors, there is less likelihood of a traumatic reaction by the patient.
The following United States patents are known to applicant, and while not particularly pertinent to the present invention are called to the examiner's attention: U.S. Pat. Nos. 3,081,765; 3,499,435, and 3,734,094. The first of these patents shows a rectal probe for monitoring a patient's breathing and temperature and utilizes a thermistor. U.S. Pat. No. 3,499,435, shows an "Esophageal Probe For Use In Monitoring" and incorporates a tube for withdrawing stomach fluids and in addition to other features incorporates a temperature probe. The last of these patents is also directed to an esophageal instrument and is provided with electrode bands encircling the tube for monitoring heart functions.